Efficiency of a Light Bulb (Pre Lab Assignment Included) Objective: An ordinary incandescent light bulb converts electrical energy into both light and heat. In the light bulb, current is made to flow through a very thin tungsten wire, causing it to get extremely hot andglow white. The wire is kept in a glass bulb which has been evacuated to prevent air from chemically reacting with it. The light energy is radiated away through the clear glass envelope, while the heat energy raises the temperature of the bulb. This week we will measure both the light and heat energy output of a light bulb. From our measurements we will calculate what fraction of the total energy goes into light – the "efficiency" of the light bulb. Note that this definition of efficiency is based on our interest, in this case, the amount of light output. Apparatus 1. Computer with Data Studiosoftware 2. PASPort temperature sensor 3. Light bulb assembly with electrical power supply 4. Digital voltmeter/ammeter 5. Support stand to hold light bulb and thermometer 6. Clear plastic vial to serve as a calorimeter 7. Electric-powered magnetic stirrer 8. Magnetic stirring rod (caution: do not lose this in the sink)9. Hot water and room temperature water 10. A 250 ml plastic beaker to fetch and weigh the water 11. Black ink
has intentionally blurred sections.
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